Very recently, while functions owned by portable telephones, notebook type computers, digital cameras, and the like are conspicuously improved, high resolution and high precision are strongly required for display elements and imaging elements which are built in these electronic appliances, so that the structures of these electronic appliances become more complex. In particular, portable telephones are strongly required to be made compact and in light weight as well as in low cost, and also required to be operable in low consumption, while camera functions are required to be built in these portable telephones and sizes of display units of the portable telephones are required to be increased. As to housing structures of these portable telephones, folded type housings called as “clam shell type housings” and “flip type housings” have been mainly employed.
Currently, in electronic apparatus containing these display member elements and imaging elements, strong demands are considerably made to manufacture large-sized display units with high resolution, and further, to make these electronic appliance compact and in lightweight. In response to these demands, there are many possibilities that element mounting boards of these electronic appliances are divided into plural sub-boards. In this case, there are many opportunities that electronic circuits are separated to a display member side and a control side. Under such a circumstance, lengths of wiring lines for connecting CPUs to either display elements or imaging elements are necessarily increased. Since resolution of display elements is increased, frequencies of signals transmitted through these line paths are increased, so that electrical connections between these electronic elements gradually become difficult.
More specifically, in clam shell type structure, CPUs are connected to either display elements or imaging elements via narrow hinge portions. Since the resolution as to these display elements and imaging elements is increased, amounts of data transmitted/received between both boards are also increased, so that high-speed data transfer techniques are required. To solve this problem, as high-speed data transfer systems, for instance, such a technical idea that LVDS (Low Voltage Differential Signaling) is used to connect either a display member or an imaging element has been proposed (Japanese Patent No. 3086456 (column 44), and Japanese Patent No. 3330359 (column 46)). Moreover, Japanese Patent No. 3349426 and Japanese Patent No. 3349490 have proposed the new methods, since the above-described LVDS technical idea cannot sufficiently solve the problem.
On the other hand, while great progress appears in semiconductor manufacturing techniques, there are such trends that integration degrees are considerably increased as a system-on-chip, and thus, all of semiconductor circuits which are storable within a single chip are mounted on this single semiconductor chip. As a result, a total number of pins used to connect semiconductor chips to external circuits are considerably increased, and occasionally exceeds several hundreds of connection pins. On the other hand, while operating frequencies of semiconductor circuits are similarly increased, the conventional connecting method for connecting the semiconductor circuit to the external unit via the wire bonding may cause a problem as to high frequency characteristics, and also may cause another problem that signals can be hardly transmitted/received between the semiconductor circuit and the external unit. With respect to such a problem, several researching reports have been made in which semiconductor chips are mutually connected by way of wireless manners, or circuit blocks are mutually connected by way of wireless methods in Japanese magazine “NIKKEI MICRODEVICE” issued in December, 2003, page 161; JP-A-10-256478; JP-A-2000-124406; JP-A-2000-68904; and JP-A-2003-101320.
However, as to recent large screen sizes of display members, even when these technical ideas are executed, sufficiently satisfiable performance could not be obtained. In other words, in small-signal serial transfer operations such as LVDS, very delicate designs as well as adjustments are required in order to achieve sufficiently satisfiable noise withstanding characteristics (interference withstanding characteristics and characteristics capable of avoiding applications of interference). In the LVDS technique, since amplitudes of signals are small, digital ICs necessarily handle analog signals. As a result, there is a problem that power consumption is increased. Also, in order to transmit signals in high precision, well-matched impedance terminations are required in the LVDS technique. However, there are a large number of signal lines which require the impedance terminations, and transfer impedances are low, e.g. 100 ohms. Accordingly, there is another problem that electric power consumed in these terminating resistances becomes not allowable values, namely becomes high.
Furthermore, in such a case that wiring lines pass through movable portions such as hinge portions, since characteristic impedances are changed due to bending degrees of these movable portions, an impedance mismatching phenomenon may occur in response to conditions, and thus, signal deteriorations may be induced because of reflections at the bending portions. As a consequence, there are other problems that speeds of data to be transferred are restricted, and/or limitations are made as to mounting methods and arrangements of components.
In addition, as apparent from the foregoing descriptions, since a total number of signals transmitted/received via the hinge portions amounts to several tens of signal lines, and wiring lines formed on boards cannot be used, flexible boards are connected to each other via connectors. There is such a drawback that the use of such a flexible board and the connection by such a connector cause high cost, and further, connection reliability is low.
Furthermore, increasing of wiring lines required for transferring data in high speeds requires physical spaces used for these wiring lines. Apparently, a large limitation is made of designs for electronic appliances.
In addition, when such large amounts of data are transferred in high speeds by using long wiring lines, if electromagnetic fields radiated from signal lines are increased, then this may cause electromagnetic interferences which are given to other electronic appliances, or the own electronic appliances. While amplitude levels at signal reception terminals have been defined in rules in signal transfer operation by the conventional signal lines, even if sufficiently high qualities are secured at the signal reception terminals, the amplitude levels of the signals cannot be lowered. In other words, EMI measures cannot be satisfactorily taken, so that this may cause designs of electronic appliances to be restricted, and may cause cost of these electronic appliances to be increased. Also, since electronic circuits on the transmission side are driven, loads on the signal reception terminals and stray capacitances of line lines are driven at the same time, so that extra energy is necessarily required so as to transfer signals. That is to say, this may increase power consumption.
These problems may be entirely solved if the conventional wireless communication techniques are conducted to communications executed among the respective blocks of electronic circuits and integrated circuits, and data transfer operations in such portions where wiring lines cannot be formed are carried out by employing wireless data transfer techniques by electromagnetic waves. In connection with the above-described conventional wireless communication technique, an attention is paid to the technical ideas which have been disclosed in Japanese magazine “NIKKEI MICRODEVICE” issued in December, 2003, page 161; JP-A-10-256478; JP-A-2000-124406; JP-A-2000-68904; and JP-A-2003-101320.
However, in order to conduct the conventional wireless technical ideas to data transfer operations within electronic appliances, mechanisms thereof are very complex and actual installations thereof can be hardly carried out, as compared with those of such a case that data have been transferred by way of conductor lines. In particular, in portable telephone terminals, power of transmitters of telephone functions (namely, principle object of portable telephone terminals) is extremely high, and thus, the transmission signals may give large disturbances to wireless connections established within the same electronic appliance (portable telephone terminal). As apparent from the foregoing explanations, as to the wireless communication executed in the same electronic appliance, only electromagnetic waves having low levels may be limitedly used which do not cause restriction subjects restricted by the Japanese electromagnetic wave control law, and the like. In fact, a difference between these signal levels is reached to 80 dB. Conversely, there are some possibilities that signals used to connect internal appliances may be mixed into telephone receivers as noise and may give disturbances thereto, for example, may lower sensitivities of these receivers. None of these conventional techniques discloses effective solving means with respect to the above-described problems.
Also, an antenna used to internally connect electronic appliances constitutes a very difficult problem when the above-described conventional wireless techniques are carried out. None of the above-described Japanese patent publications 5 to 8 describes any effective solving measure. For instance, the Japanese patent publication 6 describes that the antenna having the length equal to ¼ of the wavelength of the electromagnetic wave having the frequency of 1.5 GHz is formed on the integrated circuit. However, the wavelength of such an electromagnetic wave having the frequency of 1.5 GHz is equal to 20 cm, and thus, it is practically difficult to form such an antenna having a ¼-wavelength antenna length (namely, 5 cm) on the integrated circuit. Also, the Japanese patent publications 7 and 8 describe structures that insulating films are formed on semiconductor chips, and plane-shaped antenna radiators are positioned on the insulating films of the semiconductor chips. However, such a fact can be easily understood by ordinarily skilled engineers. That is, the electromagnetic waves cannot be effectively radiated from the antenna radiators positioned on the insulating films due to such thicknesses substantially equal to the thicknesses of the insulating films formed on the semiconductor chips.
Further, while communications are executed within electronic appliances in a point-blank range, propagations of electromagnetic waves must be considered based upon not only a far distance range where the normal communication line is applied, but also a specific propagation characteristic in the vicinity of the antenna.
To clarify this matter, a simulation executed based upon the conventional technique will now be explained with reference to drawings.
FIG. 11 is an illustration of a portable telephone terminal equipped with a clam shell structure, namely, a simulation of a portable telephone terminal which is arranged by both a display body unit 701 on which a display apparatus is mounted, and a main body unit 702 on which a baseband processor and an input apparatus (keyboard) are mounted. Although both the display body unit 701 and the main body unit 702 may be folded while a line X-X′ is used as an axis, as indicated in this drawing, a simulation is carried out under such a condition that these units 701 and 702 are opened, namely under the normal condition.
In this portable telephone terminal model, in order that data to be displayed on the display apparatus is transmitted from the main body unit 702 to the display body unit 701 by employing electromagnetic waves, both a transmission-purpose antenna 703 and a reception-purpose antenna 704 are provided thereon respectively. Also, while a transmission/reception-purpose antenna 705 of a portable telephone is provided on the display body unit 701, electric power is fed from the main body unit 702 via a coaxial cable under the normal condition. In this drawing, any of these antennas were handled as mono-pole antennas for the sake of an easy simulation. In an actual embodiment mode, such low height antennas as an inverted-F type antenna must be selected as the antennas 703 and 704. However, it is conceivable that there is no such a large difference in simulation results of two antenna cases. Also, assuming now that the portable telephone-purpose antenna 705 transmits/receives electromagnetic waves in a frequency range of 2 GHz which is used in the third generation portable telephone system, and the internal appliance communication-purpose antennas 703 and 704 use electromagnetic waves in a frequency range of 5 GHz, such cylinders are employed as radiators, the lengths of which are 37.5 mm and 15 mm and correspond to a ¼ wavelength, and the diameters of which are 1 mm.
FIG. 12 represents a typical S parameter of an S matrix in the case that the internal appliance communication-purpose transmission antenna 703 is set as a port 1, the internal appliance communication-purpose reception antenna 704 is set as a port 2, and the telephone-purpose antenna 705 is set as a port 3.
In FIG. 12, a ratio of energy transferred from the internal appliance communication-purpose transmission antenna 703 to the reception antenna 704 is “S21”, whereas a ratio of energy transferred from the portable telephone antenna 705 to the internal appliance communication-purpose reception antenna 704 is “S23.” As understood from this drawing, the ratio “S21” is approximately −16 dB in the frequency of 5 GHz used in the internal appliance communication, and the ratio “S23” is −25 dB in the frequency of 2 GHz for the portable telephone.
In other words, a level difference between the transmission power of the internal appliance communication-purpose transmission antenna 703 and the transmission power of the portable telephone-purpose antenna 705 in the internal appliance communication-purpose reception antenna 704 is directly reflected to a DU ratio (Desire/Undesire ratio). Transmission power for a portable telephone is 23 dBm in maximum, and also, maximum transmission power which is permitted to a non-licensed radio station based upon Japanese electromagnetic wave control law corresponds to −64.3 dBm converted by EIRP. In accordance with the above-described simulation, both signals appear at the internal appliance communication-purpose antenna 704 as an extremely large level difference of approximately 80 dB (23−(−64.3)−(16−25)=78.3).
In an internal appliance communication-purpose reception unit, a filter means for removing this unwanted signal is required. However, in an actual case, it is practically difficult to mount a filter capable of removing such an extremely large level difference on this reception unit. Symbol “S13” indicates a ratio of energy which is transmitted from the portable telephone-purpose antenna 705 to the internal appliance communication-purpose transmission antenna 703. since both the antennas correspond to transmission antennas, this energy ratio “S13” does not cause a problem. However, for example, in a case that image data acquired by an imaging element mounted on the display body unit 701 is transmitted to the main body unit 702 in such a portable telephone terminal equipped with the above-described imaging element, for instance, in a portable telephone equipped with a camera, the internal appliance communication-purpose antenna 703 is used as a reception-purpose antenna, and thus, a value of this energy ratio “S13” may be employed for a reference purpose. It should also be noted that since the S matrix corresponds to a symmetrical matrix, S31=S13. In this case, a condition becomes more severe, and thus, the DU ratio is reached to −90 dB.
As a consequence, the present invention has been made to solve the above-described various sorts of problems occurred when a large amount of data are transferred in high speeds and in the wireless manner between the respective circuit blocks employed in the conventional electronic appliances, and in particular, to solve the problems as to the disturbance eliminations and the sizes of the antennas in a case that the strong electromagnetic wave oscillating source is present which constitutes the principle purpose owned by the electronic appliance within the own electronic appliance, and therefore, has an object to provide both an electronic apparatus and a wireless communication terminal, which are capable of removing the drawbacks and the restrictions of the conventional data transfer system, and can be manufactured in low cost and with high reliability.